/****************************************************************************
**Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991
**              2020, KylinSoft Co., Ltd.
**All rights reserved.
**
**License to copy and use this software is granted provided that it
**is identified as the "RSA Data Security, Inc. MD5 Message-Digest
**Algorithm" in all material mentioning or referencing this software
**or this function.
**
**License is also granted to make and use derivative works provided
**that such works are identified as "derived from the RSA Data
**Security, Inc. MD5 Message-Digest Algorithm" in all material
**mentioning or referencing the derived work.
**
**RSA Data Security, Inc. makes no representations concerning either
**the merchantability of this software or the suitability of this
**software for any particular purpose. It is provided "as is"
**without express or implied warranty of any kind.
**
**These notices must be retained in any copies of any part of this
**documentation and/or software.
**
**
**
**The original md5 implementation avoids external libraries.
**This version has dependency on stdio.h for file input and
**string.h for memcpy.
**
****************************************************************************/

#ifndef __MD5_H__
#define __MD5_H__
#include <cstdio>
#include <cstring>
#include <iostream>

namespace limonp {

//#pragma region MD5 defines
// Constants for MD5Transform routine.
#define S11 7
#define S12 12
#define S13 17
#define S14 22
#define S21 5
#define S22 9
#define S23 14
#define S24 20
#define S31 4
#define S32 11
#define S33 16
#define S34 23
#define S41 6
#define S42 10
#define S43 15
#define S44 21


// F, G, H and I are basic MD5 functions.
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))

// ROTATE_LEFT rotates x left n bits.
#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

// FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
// Rotation is separate from addition to prevent recomputation.
#define FF(a, b, c, d, x, s, ac) { \
  (a) += F ((b), (c), (d)) + (x) + (UINT4)(ac); \
  (a) = ROTATE_LEFT ((a), (s)); \
  (a) += (b); \
  }
#define GG(a, b, c, d, x, s, ac) { \
  (a) += G ((b), (c), (d)) + (x) + (UINT4)(ac); \
  (a) = ROTATE_LEFT ((a), (s)); \
  (a) += (b); \
  }
#define HH(a, b, c, d, x, s, ac) { \
  (a) += H ((b), (c), (d)) + (x) + (UINT4)(ac); \
  (a) = ROTATE_LEFT ((a), (s)); \
  (a) += (b); \
  }
#define II(a, b, c, d, x, s, ac) { \
  (a) += I ((b), (c), (d)) + (x) + (UINT4)(ac); \
  (a) = ROTATE_LEFT ((a), (s)); \
  (a) += (b); \
  }
//#pragma endregion


typedef unsigned char BYTE ;

// POINTER defines a generic pointer type
typedef unsigned char *POINTER;

// UINT2 defines a two byte word
typedef unsigned short int UINT2;

// UINT4 defines a four byte word
typedef unsigned int UINT4;

static unsigned char PADDING[64] = {
    0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};
// convenient object that wraps
// the C-functions for use in C++ only
class MD5 {
private:
    struct __context_t {
        UINT4 state[4];                                   /* state (ABCD) */
        UINT4 count[2];        /* number of bits, modulo 2^64 (lsb first) */
        unsigned char buffer[64];                         /* input buffer */
    } context ;

    //#pragma region static helper functions
    // The core of the MD5 algorithm is here.
    // MD5 basic transformation. Transforms state based on block.
    static void MD5Transform(UINT4 state[4], unsigned char block[64]) {
        UINT4 a = state[0], b = state[1], c = state[2], d = state[3], x[16];

        Decode(x, block, 64);

        /* Round 1 */
        FF(a, b, c, d, x[ 0], S11, 0xd76aa478);  /* 1 */
        FF(d, a, b, c, x[ 1], S12, 0xe8c7b756);  /* 2 */
        FF(c, d, a, b, x[ 2], S13, 0x242070db);  /* 3 */
        FF(b, c, d, a, x[ 3], S14, 0xc1bdceee);  /* 4 */
        FF(a, b, c, d, x[ 4], S11, 0xf57c0faf);  /* 5 */
        FF(d, a, b, c, x[ 5], S12, 0x4787c62a);  /* 6 */
        FF(c, d, a, b, x[ 6], S13, 0xa8304613);  /* 7 */
        FF(b, c, d, a, x[ 7], S14, 0xfd469501);  /* 8 */
        FF(a, b, c, d, x[ 8], S11, 0x698098d8);  /* 9 */
        FF(d, a, b, c, x[ 9], S12, 0x8b44f7af);  /* 10 */
        FF(c, d, a, b, x[10], S13, 0xffff5bb1);  /* 11 */
        FF(b, c, d, a, x[11], S14, 0x895cd7be);  /* 12 */
        FF(a, b, c, d, x[12], S11, 0x6b901122);  /* 13 */
        FF(d, a, b, c, x[13], S12, 0xfd987193);  /* 14 */
        FF(c, d, a, b, x[14], S13, 0xa679438e);  /* 15 */
        FF(b, c, d, a, x[15], S14, 0x49b40821);  /* 16 */

        /* Round 2 */
        GG(a, b, c, d, x[ 1], S21, 0xf61e2562);  /* 17 */
        GG(d, a, b, c, x[ 6], S22, 0xc040b340);  /* 18 */
        GG(c, d, a, b, x[11], S23, 0x265e5a51);  /* 19 */
        GG(b, c, d, a, x[ 0], S24, 0xe9b6c7aa);  /* 20 */
        GG(a, b, c, d, x[ 5], S21, 0xd62f105d);  /* 21 */
        GG(d, a, b, c, x[10], S22,  0x2441453);  /* 22 */
        GG(c, d, a, b, x[15], S23, 0xd8a1e681);  /* 23 */
        GG(b, c, d, a, x[ 4], S24, 0xe7d3fbc8);  /* 24 */
        GG(a, b, c, d, x[ 9], S21, 0x21e1cde6);  /* 25 */
        GG(d, a, b, c, x[14], S22, 0xc33707d6);  /* 26 */
        GG(c, d, a, b, x[ 3], S23, 0xf4d50d87);  /* 27 */
        GG(b, c, d, a, x[ 8], S24, 0x455a14ed);  /* 28 */
        GG(a, b, c, d, x[13], S21, 0xa9e3e905);  /* 29 */
        GG(d, a, b, c, x[ 2], S22, 0xfcefa3f8);  /* 30 */
        GG(c, d, a, b, x[ 7], S23, 0x676f02d9);  /* 31 */
        GG(b, c, d, a, x[12], S24, 0x8d2a4c8a);  /* 32 */

        /* Round 3 */
        HH(a, b, c, d, x[ 5], S31, 0xfffa3942);  /* 33 */
        HH(d, a, b, c, x[ 8], S32, 0x8771f681);  /* 34 */
        HH(c, d, a, b, x[11], S33, 0x6d9d6122);  /* 35 */
        HH(b, c, d, a, x[14], S34, 0xfde5380c);  /* 36 */
        HH(a, b, c, d, x[ 1], S31, 0xa4beea44);  /* 37 */
        HH(d, a, b, c, x[ 4], S32, 0x4bdecfa9);  /* 38 */
        HH(c, d, a, b, x[ 7], S33, 0xf6bb4b60);  /* 39 */
        HH(b, c, d, a, x[10], S34, 0xbebfbc70);  /* 40 */
        HH(a, b, c, d, x[13], S31, 0x289b7ec6);  /* 41 */
        HH(d, a, b, c, x[ 0], S32, 0xeaa127fa);  /* 42 */
        HH(c, d, a, b, x[ 3], S33, 0xd4ef3085);  /* 43 */
        HH(b, c, d, a, x[ 6], S34,  0x4881d05);  /* 44 */
        HH(a, b, c, d, x[ 9], S31, 0xd9d4d039);  /* 45 */
        HH(d, a, b, c, x[12], S32, 0xe6db99e5);  /* 46 */
        HH(c, d, a, b, x[15], S33, 0x1fa27cf8);  /* 47 */
        HH(b, c, d, a, x[ 2], S34, 0xc4ac5665);  /* 48 */

        /* Round 4 */
        II(a, b, c, d, x[ 0], S41, 0xf4292244);  /* 49 */
        II(d, a, b, c, x[ 7], S42, 0x432aff97);  /* 50 */
        II(c, d, a, b, x[14], S43, 0xab9423a7);  /* 51 */
        II(b, c, d, a, x[ 5], S44, 0xfc93a039);  /* 52 */
        II(a, b, c, d, x[12], S41, 0x655b59c3);  /* 53 */
        II(d, a, b, c, x[ 3], S42, 0x8f0ccc92);  /* 54 */
        II(c, d, a, b, x[10], S43, 0xffeff47d);  /* 55 */
        II(b, c, d, a, x[ 1], S44, 0x85845dd1);  /* 56 */
        II(a, b, c, d, x[ 8], S41, 0x6fa87e4f);  /* 57 */
        II(d, a, b, c, x[15], S42, 0xfe2ce6e0);  /* 58 */
        II(c, d, a, b, x[ 6], S43, 0xa3014314);  /* 59 */
        II(b, c, d, a, x[13], S44, 0x4e0811a1);  /* 60 */
        II(a, b, c, d, x[ 4], S41, 0xf7537e82);  /* 61 */
        II(d, a, b, c, x[11], S42, 0xbd3af235);  /* 62 */
        II(c, d, a, b, x[ 2], S43, 0x2ad7d2bb);  /* 63 */
        II(b, c, d, a, x[ 9], S44, 0xeb86d391);  /* 64 */

        state[0] += a;
        state[1] += b;
        state[2] += c;
        state[3] += d;

        // Zeroize sensitive information.
        memset((POINTER)x, 0, sizeof(x));
    }

    // Encodes input (UINT4) into output (unsigned char). Assumes len is
    // a multiple of 4.
    static void Encode(unsigned char *output, UINT4 *input, unsigned int len) {
        unsigned int i, j;

        for(i = 0, j = 0; j < len; i++, j += 4) {
            output[j] = (unsigned char)(input[i] & 0xff);
            output[j + 1] = (unsigned char)((input[i] >> 8) & 0xff);
            output[j + 2] = (unsigned char)((input[i] >> 16) & 0xff);
            output[j + 3] = (unsigned char)((input[i] >> 24) & 0xff);
        }
    }

    // Decodes input (unsigned char) into output (UINT4). Assumes len is
    // a multiple of 4.
    static void Decode(UINT4 *output, unsigned char *input, unsigned int len) {
        unsigned int i, j;

        for(i = 0, j = 0; j < len; i++, j += 4)
            output[i] = ((UINT4)input[j]) | (((UINT4)input[j + 1]) << 8) |
                        (((UINT4)input[j + 2]) << 16) | (((UINT4)input[j + 3]) << 24);
    }
    //#pragma endregion


public:
    // MAIN FUNCTIONS
    MD5() {
        Init() ;
    }

    // MD5 initialization. Begins an MD5 operation, writing a new context.
    void Init() {
        context.count[0] = context.count[1] = 0;

        // Load magic initialization constants.
        context.state[0] = 0x67452301;
        context.state[1] = 0xefcdab89;
        context.state[2] = 0x98badcfe;
        context.state[3] = 0x10325476;
    }

    // MD5 block update operation. Continues an MD5 message-digest
    // operation, processing another message block, and updating the
    // context.
    void Update(
        unsigned char *input,   // input block
        unsigned int inputLen) {  // length of input block
        unsigned int i, index, partLen;

        // Compute number of bytes mod 64
        index = (unsigned int)((context.count[0] >> 3) & 0x3F);

        // Update number of bits
        if((context.count[0] += ((UINT4)inputLen << 3))
                < ((UINT4)inputLen << 3))
            context.count[1]++;
        context.count[1] += ((UINT4)inputLen >> 29);

        partLen = 64 - index;

        // Transform as many times as possible.
        if(inputLen >= partLen) {
            memcpy((POINTER)&context.buffer[index], (POINTER)input, partLen);
            MD5Transform(context.state, context.buffer);

            for(i = partLen; i + 63 < inputLen; i += 64)
                MD5Transform(context.state, &input[i]);

            index = 0;
        } else
            i = 0;

        /* Buffer remaining input */
        memcpy((POINTER)&context.buffer[index], (POINTER)&input[i], inputLen - i);
    }

    // MD5 finalization. Ends an MD5 message-digest operation, writing the
    // the message digest and zeroizing the context.
    // Writes to digestRaw
    void Final() {
        unsigned char bits[8];
        unsigned int index, padLen;

        // Save number of bits
        Encode(bits, context.count, 8);

        // Pad out to 56 mod 64.
        index = (unsigned int)((context.count[0] >> 3) & 0x3f);
        padLen = (index < 56) ? (56 - index) : (120 - index);
        Update(PADDING, padLen);

        // Append length (before padding)
        Update(bits, 8);

        // Store state in digest
        Encode(digestRaw, context.state, 16);

        // Zeroize sensitive information.
        memset((POINTER)&context, 0, sizeof(context));

        writeToString() ;
    }

    /// Buffer must be 32+1 (nul) = 33 chars long at least
    void writeToString() {
        int pos ;

        for(pos = 0 ; pos < 16 ; pos++)
            sprintf(digestChars + (pos * 2), "%02x", digestRaw[pos]) ;
    }


public:
    // an MD5 digest is a 16-byte number (32 hex digits)
    BYTE digestRaw[ 16 ] ;

    // This version of the digest is actually
    // a "printf'd" version of the digest.
    char digestChars[ 33 ] ;

    /// Load a file from disk and digest it
    // Digests a file and returns the result.
    const char* digestFile(const char *filename) {
        if(NULL == filename || strcmp(filename, "") == 0)
            return NULL;

        Init() ;

        FILE *file;

        unsigned char buffer[1024] ;

        if((file = fopen(filename, "rb")) == NULL) {
            return NULL;
        }
        int len;
        while((len = fread(buffer, 1, 1024, file)))
            Update(buffer, len) ;
        Final();

        fclose(file);

        return digestChars ;
    }

    /// Digests a byte-array already in memory
    const char* digestMemory(BYTE *memchunk, int len) {
        if(NULL == memchunk)
            return NULL;

        Init() ;
        Update(memchunk, len) ;
        Final() ;

        return digestChars ;
    }

    // Digests a string and prints the result.
    const char* digestString(const char *string) {
        if(string == NULL)
            return NULL;

        Init() ;
        Update((unsigned char*)string, strlen(string)) ;
        Final() ;

        return digestChars ;
    }
};

inline bool md5String(const char* str, std::string& res) {
    if(NULL == str) {
        res = "";
        return false;
    }

    MD5 md5;
    const char *pRes = md5.digestString(str);
    if(NULL == pRes) {
        res = "";
        return false;
    }

    res = pRes;
    return true;
}

inline bool md5File(const char* filepath, std::string& res) {
    if(NULL == filepath || strcmp(filepath, "") == 0) {
        res = "";
        return false;
    }

    MD5 md5;
    const char *pRes = md5.digestFile(filepath);

    if(NULL == pRes) {
        res = "";
        return false;
    }

    res = pRes;
    return true;
}
}
#endif
